Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue Madison, Wisconsin 53706, United States.
D.O.E. Great Lakes Bioenergy Research Center, The Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, Wisconsin 53726, United States.
J Am Chem Soc. 2021 Sep 22;143(37):15462-15470. doi: 10.1021/jacs.1c08635. Epub 2021 Sep 9.
Biomass pretreatment methods are commonly used to isolate carbohydrates from biomass, but they often lead to modification, degradation, and/or low yields of lignin. Catalytic fractionation approaches provide a possible solution to these challenges by separating the polymeric sugar and lignin fractions in the presence of a catalyst that promotes cleavage of the lignin into aromatic monomers. Here, we demonstrate an oxidative fractionation method conducted in the presence of a heterogeneous non-precious-metal Co-N-C catalyst and O in acetone as the solvent. The process affords a 15 wt% yield of phenolic products bearing aldehydes (vanillin, syringaldehyde) and carboxylic acids (-hydroxybenzoic acid, vanillic acid, syringic acid), complementing the alkylated phenols obtained from existing reductive catalytic fractionation methods. The oxygenated aromatics derived from this process have appealing features for use in polymer synthesis and/or biological funneling to value-added products, and the non-alkaline conditions associated with this process support preservation of the cellulose, which remains insoluble at reaction conditions and is recovered as a solid.
生物质预处理方法常用于从生物质中分离碳水化合物，但这些方法通常会导致木质素的修饰、降解和/或低产率。催化分级方法通过在促进木质素裂解为芳香单体的催化剂的存在下分离聚合物糖和木质素部分，为这些挑战提供了一种可能的解决方案。在这里，我们展示了一种在非均相非贵金属 Co-N-C 催化剂和 O 的存在下在丙酮中进行的氧化分级方法作为溶剂。该过程提供了 15wt%的酚类产物，其中含有醛（香草醛、丁香醛）和羧酸（-羟基苯甲酸、香草酸、丁香酸），补充了现有还原催化分级方法获得的烷基酚。该过程中得到的含氧芳烃具有用于聚合物合成和/或生物通道化至增值产品的诱人特征，并且与该过程相关的非碱性条件支持纤维素的保存，纤维素在反应条件下仍不溶，并作为固体回收。
